Djokovic sailed through the previous round but did have a bit of a hiccup against against Jerzy Janowicz in his opening match.

A decent contest is foreseeable given Djokovic’s struggles against Youzhny, leading the head-to-head 6-3.

SPORT360 VERDICT: Djokovic in three.

MADISON KEYS (USA) vs NAOMI OSAKA (JPN)

Osaka beat Coco Vandeweghe in her opener and will eager to pull off another upset. The 18 year-old is a good counter-puncher and while that’s a great asset to have against Keys, it may not be enough.

The American won’t have it all her own way but should show her class and overpower the Japanese in due course.

SPORT360 VERDICT: Keys in three.

RAFAEL NADAL (ESP) vs ANDRIY KUZNETSOV (RUS)

NADAL (ESP) vs KUZNETSOV (RUS)

5 - WORLD RANKING - 47

3 - HEAD TO HEAD - 0

69 - CAREER TITLES - 0

34-11 2016 WIN-LOSS - 22-16

Nadal got through the first two rounds in straight sets while Kuznetsov is coming off a straight sets win over Albert Ramos-Vinolas as well.

The Spaniard has had a few concerns over his wrist but hasn’t been made to stretch himself so far and should be fine. He won all three of his previous meetings with the Russian, two in straight sets.

SPORT360 VERDICT: Nadal in straight sets.

ANGELIQUE KERBER (GER) vs CATHRINE BELLIS (USA)

At just 17, Bellis faces a mammoth task as she takes on the world number two. It was only two years ago that the American sent shockwaves through the tournament having beaten Dominika Cibulkova as a 15 year-old.

Kerber however appears to be playing like she owns the court and anything other than a victory for the German seems ludicrous.

SPORT360 VERDICT: Kerber in straight sets.

MARIN CILIC (CRO) vs JACK SOCK (USA)

CILIC (CRO) vs SOCK (USA)

9 - WORLD RANKING - 27

0 - HEAD TO HEAD - 1

15 - CAREER TITLES - 1

32-17 2016 WIN-LOSS 22-15

In their only previous meeting, Sock came from behind in the Davis Cup two months to win 6-4 in the fifth set.

However, Cilic has been in great form since and should come out on top despite Sock’s home court advantage.

Perhaps not, but a simple records check will tell you what all of them have in common. They are American tennis players who received wildcard entries to the 2014 and 2015 US Open main draw. In both of those years, Juan Martin Del Potro was missing, nursing a troublesome left wrist that, for the second time in his career, forced him out of full seasons on the ATP Tour. Juan Martin Del Potro. Heard of him, right?

Well, after playing effectively no competitive tennis for two-and-a-half years, Del Potro made the main draw at Wimbledon earlier this year, and reached the third round, knocking out World No. 3 and two-time Grand Slam champion Stanislas Wawrinka along the way. At the Olympics, he defeated Novak Djokovic in straight sets in the first round, Rafael Nadal in the semis and pushed Andy Murray to four sets in arguably the match of the season before having to settle for silver in Rio.

The United States Tennis Association (USTA) rather liked what they saw, and handed Del Potro, the 2009 champion at Flushing Meadows, one of their eight wildcards. So far, so routine.

Not as far as top-ranked male American player Steve Johnson was concerned, though. The 19th seed described Del Potro as “a phenomenal guy, a phenomenal tennis player”, but was unhappy at the wildcard not instead being awarded to yet another American, half a dozen of whom are still beneficiaries this year. Michael Mmoh, Mackenzie McDonald, Ernesto Escobedo… you get the point. And then Johnson went on to the part of his argument he presumably thought was the clincher. “What if he plays me first round? What if he wins? Or he plays Sam [Querrey] – anybody – and he beats an American?”

The idea of wildcards in tennis is an inherently unsettling concept, and one that rarely seems to be convincingly justified. It is an excuse for elitism and the subversion of meritocracy, based on the idea that some players, especially if they’re from Australia, France, the United Kingdom or the United States (the countries that host the Grand Slams), deserve a better chance than others.

DEL POTRO AT GRAND SLAMS

Australian Open: QF (2012)

French Open: SF (2009)

Wimbledon: SF (2013)

US Open: Won (2009)

So at the Grand Slams, eight players find themselves queue-jumped by players supposedly more important because they’re younger, more talented, or from the host country. This especially rankles because the players that miss out are the sort whose careers live and die by their Grand Slam appearances, both financially and in terms of ranking points. If that teenager from Melbourne, Marseille, Manchester or Miami is really all that gifted, he’ll surely let his ranking points do the talking before long.

The only saving grace for wildcards comes in circumstances where people like Del Potro end up needing one. This is a player clearly unsuited to his official ranking of 141, where he finds himself through sheer hard luck. Providing wildcards to players who enhance the appeal of the tournament, or improve the quality of its field, is a perfectly legitimate way to use them, and can anyone – Steve Johnson included – argue that the men’s draw is better off without the 2009 champion in it?

Johnson’s fears turned out to be deliciously prescient, because, not long after his remarks, the draw that came out pitted the American against the Argentine in the second round. As the two men were introduced to the Arthur Ashe crowd under the lights, it became obvious how much Johnson’s concerns that Del Potro’s wildcard ‘might make a lot of American fans upset’ were misplaced. While the American received a respectful ovation upon walking in, the crowd went wild, New York style, as Del Potro set foot on the court that has seen his greatest success. He hadn’t hit a shot yet, but the memories of that magical night in 2009 that saw him tame the wizardry of a then-unbeatable Federer had already been conjured up.

He didn’t need to be as good as that on Thursday night, and he wasn’t. But it was still good enough to comfortably see off the Californian and march on to the third round. As he walked off the court, the fans mobbed him, eager to get their autographs and selfies. Nobody appeared too upset, who could begrudge this gentle giant his run of good form, or argue he hadn’t earned his place?

He vindicated the USTA’s decision to award him the wildcard, because his capability to do so is exactly why he was handed it in the first place. He has already demonstrated how misleading his ranking is at present, and how out of place he would have looked playing three rounds of qualifying. More out of place than Dennis Novikov or Bjorn Fratangelo, players whom Steve Johnson would presumably rather the wildcard went to.

Getting back to Johnson, he horribly misjudged the public perception on Del Potro’s presence in the main draw, instead echoing a viewpoint that has perniciously come to be accepted without needing to be argued for in tennis circles. The American was absolutely right to be concerned about how wildcards are awarded at the Grand Slams, but the man he lost to under the bright lights of New York certainly isn’t part of the problem.